The present invention relates to a frame for a vehicle seat and more particularly, to a seat support crosspiece that is formed as an element that shortens by a preset amount along its longitudinal dimension when a load is imposed up to a threshold value, and that further includes an intentional bending point that bends out under load perpendicular to the longitudinal direction exceeding a threshold value so that the crosspiece does not move in the direction of the supporting surface.
A frame of a known type (JP 1 11 05 602 A) is stiffened by a one-piece crosspiece. The crosspiece is supposed to reduce deformation of the frame during a lateral vehicle collision. If a threshold load is exceeded, the crosspiece becomes deformed in an uncontrolled manner at an uncontrolled point along with the rest of the frame. Such uncontrolled deformation creates a hazard both for the seat occupant and for other vehicle passengers.
It is further known to provide a vehicle seat with a crosspiece of variable length (EP 0 983 910 A1) that is designed to join with neighboring supporting elements connected to the vehicle body in case of a crash. This design is intended to stiffen the passenger compartment during a lateral impact by means of the cross support.
Based on the state of the art mentioned initially, it is the task of the invention to configure a vehicle seat frame so that it deforms in a controlled manner that is not hazardous to the occupant or other vehicle passengers during a lateral impact.
The present invention features a cross-brace in a vehicle seat that will deform and bend in a predetermined way during an impact situation. Deformation energy from the impact is absorbed during a first phase by means of the shortening to the crosspiece resulting at the inception of frame deformation. During this first phase, the crosspiece is merely shortened. After completion of the first phase and upon transgression of a prescribed shortening path, the crosspiece bends in a controlled manner, namely in such a manner that the danger of injury to vehicle passengers is minimized.
Formation of the crosspiece from two telescoping friction-fit partially overlapping tubes is particularly advantageous. Surrounding corrugations are pressed into the overlapping areas of the two tubes after they are telescoped.